What is the role of route preference?

A. It is used as a tiebreaker when the same prefix is available through multiple protocols.

B. It is used to determine the preferred path to a given destination.

C. It is used to select the best route between multiple equal-cost paths.

D. It is used to select which routing table to use for forwarding.

Alternate and Tiebreaker Preferences

The Junos OS provides support for alternate and tiebreaker preferences, and some of the routing protocols, including BGP and label switching, use these additional preferences. With these protocols, you can specify a primary route preference (by including the preference statement in the configuration), and a secondary preference that is used as a tiebreaker (by including the preference2 statement). You can also mark route preferences with additional route tiebreaker information by specifying a color and a tiebreaker color (by including the color and color2 statements in the configuration).

Note: The routing protocol process generally determines the active route by selecting the route with the lowest preference value.

The preference value is used to select routes to destinations in external autonomous systems (ASs) or routing domains; it has no effect on the selection of routes within an AS (that is, within an interior gateway protocol [IGP]). Routes within an AS are selected by the IGP and are based on that protocol-s metric or cost value.

References: https://www.juniper.net/techpubs/en_US/junos12.1/topics/concept/routing-protocols-route-preferences-overview.html#id-10195528